Crane command circuit having check means for detecting relay malfunction



Oct. 29, 1968 DELIBAN 3,408,546

R. CRANE COMMAND CIRCUIT HAVING CHECK MEAN FOR DETECTING RELAY MALFUNCTION Filed June 7, 1965 5 Sheets-Sheet l YAO RECEIVER DECODER RECEIVER 'QS 22 4 aeq l 28 FRAME REF. DETECTOR RATE MONITOR MONITOR FIG. I 30 32 +||5v. 53 M TROLLEY ON-OFF +24v. 452

' MDI M rr R 0%? CKT. 78

so 8 GRD. 54

"av. 52) NFL "2 23ov0c I06 0 I A INVENTOR ROBERT DELIBAN BYfl f A 94 m ATTYS.

0d. 29, 1968 DEUBAN 3,408,546

R. CRANE COMMAND CIRCUIT HAVING CHECK MEANS FOR DETECTING RELAY MALFUNCTION Filed June 7, 1965 3 Sheets-Sheet 2 200 208 COD COD TO TROLLEY INVENTOR ROBERT DELIBAN BY m l4 [flaw n4 AT TYS.

United States Patent ABSTRACT OF THE DISCLOSURE T Crane control system having a portable transmitter which sends word message comprised of three discrete signal commands to a crane mounted receiver. Crane operation occurs only if three different controls operate in tandem. Checking circuits monitor critical relays for restoration prior to crane operation, and prevent nonoperation if malfunction is detected.

The present invention is directed to a remote control system for an overhead crane, and more particularly to a system which permits a single operator located on the floor of a service area to control the operations of an overhead crane by remote control. I

' In the more conventional type of installation, an overhead crane system will include a pair of overhead tracks which are mounted above and extend along the length of the area to be serviced. A support or bridge structure extends transversely between the tracks, and a reversible bridge motor is selectively energized to drive the bridge along the tracks to different positions above the service area. A trolley structure carried by the bridge is selectively operated along the bridge member (i.e., transversely of the tracks) by a reversible trolley motor. A hoist member carried by the trolley is selectively operable in a direction upwardly and downwardly by a reversible hoist motor. A cab housing for an operator is mounted on the bridge, and control circuitry and levers within the housing permit the operator to selectively operate the bridge, trolley and hoist motors at different speeds alone and in different combinations.

The advantages of such type system are well known, and most factories of any size are equipped with an overhead material handling system of such type. In the use thereof, however, it has been necessary for one operator to ride in the cab for the purpose of operating the controls located in the cab. In most instances, it has also been necessary to have an assistant on the floor of the service area for the purpose of signalling the operator in the cab as to the movements of the overhead system required to perform the desired material handling operation.

Such manner of signalling leaves something to be desired. That is, since the end result is dependent upon a man-to-man-to-machine translation of information, the degree of control which may be achieved is definitely limited. Further, there is a loss of time in the transmission and translation of the information to the final control which increases the possibility of improper material handling.

There is a need therefore for a system which is capable of being controlled by one operator, and preferably by an operator located closely adjacent the position at which the work is to be performed. Such arrangement, in addition to eliminating the several translations of information from the observer through an operator to a machine, makes possible a more accurate and instantaneous control That is, the operator being close to the work can effect any control in a matter of time which is limited only by his own response reflexes.

While the provision of such equipment would be advantageous, the practical use thereof is dependent upon the ability to provide a system of extreme safety and reliability. That is, the nature of the loads (heavy steel objects, molten metal, etc.) which are handled in the factories is such that even the slightest malfunction could result in serious injury or loss of life. At a minimum, the improper handling of the load could result in irreparable damage to the load and equipment in the area.

It is an object of the present invention, therefore, to provide a novel radio remote control system having extremely safe and reliable circuitry for operating overhead cranes responsive to signals transmitted under the control of an operator on the floor of the area to be serviced to a receiver control unit on the crane.

It is yet another object of the invention to provide a system of such type in which the receiver control unit includes three separate groups of controls, and means for effecting a crane motor control only responsive to tandem operation of the three groups of controls in response to the receipt of three discrete signal commands in a word message.

It is a further object of the invention to provide a novel control circuit havin relay control circuitry which, from a safety standpoint approaches an A.C. coupled system in operation.

More specifically, as known in the art, A.C. coupled systems are inherently safe. Theoretically, in a command circuit adapted for use with a crane system, A.C. cou pling could be carried all the way from the source to the drive motors. However, in the field such arrangement would not be practical from a cost standpoint. In the interest of practicality, therefore, the alternating current is extended to the contactors which run the motors by introducing intermediate relay and contactor stages between the source and the motors. The problem then becomes one of making these intermediate relay and contactor stages as reliable as A.C. coupled circuits. Since it is not practical to use the principle of energy storage (which allows an A.C. coupled system to go to zero outp'ut regardless of which of two states the system may fail), the

invention discloses dual controls on all the important D.C.

coupled and relay circuits. This degree of redundancy greatly improves the probability of fail-safe ,operation since both circuits must fail in the on state to be unsafe.

To secure the maximum advantage from this duality of controls, the circuit must become inoperative as soon as possible after the first unsafe failure. Since the existence of an unsafe failure cannot be determined in the on status, it follows that the system must be turned off (even if only momentarily) as often as practical to detect a failure. In accordance with a further inventive concept a substantial number of the crucial relays and contactors up to the actual drive motors are momentarily turned off as often as practical to minimize the time between excessive failure checks. As a result the relay circuits become almost equivalent in reliability to an A.C. coupled system. The original crane contactors and control circuits are excluded since adequate reliance may be placed thereon.

In determining the practical rate of turnoff, the normal operation of the crane is used to determine the checking rate (i.e., rather than an arbitrarily selected faster rate). That is, one group of relays is checked each time the motor control levers are returned to the neutral position. Another group, associated with the main contactor of the crane, is checked after a longer interval; namely, whenever the main power switch on the control transmitter is thrown to the off position. In such manner, a high degree of safety and reliability are included in the system.

It is yet another object of the invention to provide reliable means for checking the condition of the relays in the ,forthe purpose I I parent to the skilled that other arran-gements Including embodiment set forth herein, conventional relays are used in which the contacts are either in the on or the off position-.:i,e., never in the same position, at the same time. The circuitry is thus connected to monitor the contacts, at times, in the off position prior to initiating a further control, and at other times in the on pos1t1on of maintainingthe control. It will be apmonitoring of the relay contacts with superimposed AC.

or DlC, pilot signal s, arranging the relay circuits in a balanced configuration and monitoringxfor a n unbalance in the event of a malfunction, the ,on position of the relay and other systems in which may be directly monitored, can'be used to provide a check of the contacts accordingfto the aforedescribed concepts ofthe invention.

It is yet another object of the'invention to provide a receiver control unit of such type which includes means responsive only to repetition of one; of said discretesignal "commands a predetermined plurality of time s. It is a specific object of the invention to provide a receiver control unit of such type which includes a relay checking system for at least one control group which provides posi- .tive protection against operation of the system in the event of malfunction of any of the relays or relay contacts of .the group, and specifically novel means for determining the condition of the relays and relay contacts prior to each control operation.

It is a further specific object of the invention to provide a novel system of such type which includes redundant relay means connected with such protective circuit to provide normal turnoff in the event of a relay malfunction, and to prevent reope'ration of the relay means until such time as the malfunction is cleared.

These and other objects and advantages of the present tective circuits of such equipment.

GENERAL SYSTEM DESCRIPTION The crane control system includes a control transmitter for selectively transmitting coded signals to a receiver unit located on an overhead crane. Control means on the crane selectively operate the crane bridge, trolley and hoist motors a's commanded by the signals, and further adjust the speed of the motors to different values with receipt of coded signals requesting such adjustment.

"The transmitter 4 (as shown in FIGURE 1A) includes an on-off switch, and a plurality of levers, such as Trolley, Bridge, Hoist, each of which is operable to a first position F to transmit signals which control an associated motor to rotate in the forward direction, and to' a second position R to control the rotation of the motor in the reverse direction. Each of the levers Trolley, Bridge and Hoist has a second lever, such as lever 6, associated therewith which is movable to a plurality of different positions, such as illustrated positions S1, S5, each of the different positions providing coded signals which result in the corresponding adjustment of the speed of the motor which is controlled by the associated one of the levers Trolley, Bridge and Hoist. All motors can be operated simultaneously or as desired. A nickel, cadmium battery pack (not shown) provides the power source for the transmitter. The transmitter in one embodiment was-operative to generate carrier signals at a 27,000 kc. rate and modulating pulse frequencies were generated at a 300-cycle rate to provide a modulation envelope on the higher frequency radio signal in accordance with well-known radio trans- Idifferent;groupsratlsuch rate.r,Ac.c.ording.to.one preferred.

..mission signallingreceivers.tThesignals generated bythe transmitter are a form of; pulse code modulation, the signals being coded at the transmitter into pulses, and then decoded at the receiver to recover the original voice frequencies. f P

One particularly successful code which has been used is shown in FIGURE 31 As there showrue'ach modulated signal or wire consists .of .thir tly-two'. time p'eric ds, .each of which is assigned a different..channe l number. Each modulated signal -.of. thirty-two-time ,-periods further includes a frame :marker to identify thebeg-in'ning of each signal (channel -30),=afraine ?A marker (channels 31 and 32) and a frame fB marl er(channels 1 and 2). An acceptable signal must therefore start with a frame marker piilseX'chzitinel 30) for the 'firs't tinie period, a pair ofpulses (frame A) for the succeeding two periods (channels 31, 32) and-the absence of a .pulse foLthe-next two time periods (channels 1, 2). v ;j

. A pulse is transmitted in channel 3 whenever afword or command is being sent, and a pulse -is transmittedin channel 4 in the absence of a command. The absence or presence of either of these pulses at; the wrong time invalidates the entire signal. In the absence of a command (or normal) pulse'inany' time period the unit transmits a synchronizingtpulse which has .a duration one=half that of the normal pulse (see time periods 5-29 in FIG- URE 3). As will be shown, the synchronizing pulses are ignored by all of the circuits except the repetition rate detector 28 (FIGURE 1).

By transmitting the command pulsesfat correspondingly different time periods in a signal, coded messages or instructions can be provided to the receiver equipment. In the signal shown in'FIGURE 3, the time periods 30-32 are used for marker purposes as explained above, time period 3 is used to control a safety operate circuit 160, time period 4 is used to control a safety standby circuit 138. A command pulse wouldbe transmitted in time period 5 to control rotation of the trolley motor in a forward directionv and in time period 6 to control'rota; tionv of the trolley motor in a reverse direction. A

command pulse in time period 10 will control rotation of the trolley motor at speed 2, and a. command pulse in time period 11 will control the trolley motor to. operate at speed 3. In a similar manner, command pulse in time periods 7, 8 will enable the bridge motor to move the bridge in a forward and reverse direction respectively, and pulses in time periods 14, 15 will effect operation thereof at speeds 2 and 3 respectively. A pulse in channel 25 will energize the hoist motor to raise the unit, and a pulse in channel. 26 causes the hoist to lower, the operations being accomplished at speeds 2 and3 respectively by command pulses in time periods 18, 19 respectively. Channels 9, 17 as shown are used for auxil- Iary controls. p r

The manner in which the receiver equipment of FIG- URES' l-3 is operative to provide control', of the crane motors in response to the receipt of these different commands is now set forth in detail.

SPECIFIC DESCRIPTION OFRECEIVER OPERATION 1 With reference to FIGURES 1-3 of the drawings, the radio receiver equipment is shown to include an antenna 10, a radio receiver 12 including an IF amplifier 1 6, the output of which is connected over path 18 to the decoder circuit 201 When the transmitter on-offleyeris moved to the =ON position pulse codemodulatedsignals are repeatedly generated by the'transmitter and radiated for reception by the receiver 12. After amplification, the signals are demodulated and the original pulse envelope is extracted in the divider circuit 20. The resultant video signal is provided over a first path 22 to'safetyoperate circuit 160, safety standby circuit 138, and each of the channel detector circuits 305-329. I

The signal output of decoder circuit 20 is also ex-' tended over path 24 to frame detector monitor circuit 26 and repetition rate monitor circuit 28, the respective outputs 30, 32 of which are connected to monitor output circuit 34. As will be shown, when certain conditions obtain, the monitor output circuit 34 provides an enabling signal over conductor 36 to the control circuitry (FIGURES 1-3) for the crane motor contactors (FIG- URE 3). The monitor output circuit 34 also provides a holding signal over conductor 38 as will be described.

Frame detector 26 measures the four different time periods of the frame pattern (time periods 30, 31, 32, 1, 2) and checks the time between the occurrence of the incoming frame marker pattern and the succeeding frame marker pattern, and repeats such measurement approximately ten times. If the frame is detected ten times in sequence in this manner, the frame detector monitor 26 provides an enabling signal over conductor 30 to monitor output circuit 34 to prepare the circuit for operation. As noted above, each time period in a signal has either a command pulse or a synchronization pulse, the synchronization pulse being approximately one-half the duration of the command pulse. Repetition rate monitor 28 is operative to check the occurrence of synchronization and command pulses (each of the other circuits, such as a frame detector monitor circuit 26, safety operate circuit 160, safety standby circuit 138 and pulse detector circuits 305-319 are nonresponsive to the sync pulses because of their shorter duration).

The repetition rate monitor circuit 28 checks at least 100 of these synch pulses (three successive signals of approximately thirty-two pulses for Width and spacing), and in the event the pulses pass the width and spacing check, an enabling signal is provided over conductor 32 to the monitor output circuit 34. In the event that the frame detector monitor circuit 26 has also provided an enabling signal over conductor 30, an acceptable pattern has been received, and the monitor output circuit 34 which basically comprises an A.C. gate operating on the incoming signal over conductor 32 and operated by the enabling signal on conductor 30.

If the pulse pattern received meets the requirements of the frame detector monitor circuit 26 and the repetition rate monitor circuit 28, the signals over paths 30, 32 energize monitor output circuit 34 to provide an enabling signal over conductor 36 to the master drive control group which includes monitor drive circuit 40, master start relay 46, master drive circuit 68, driving relays 74, 82 and master relays 84, 94. As will be shown, if capacitor 60 is charged by a complete circuit through back contacts 124, 130, 102 and 72, the master drive control group turns on the main contactor 108 to provide 230 volt DC. power from the source conductor 104-106 to the conductors 114, 116 and the contactors for the crane motors (FIGURE 3). A master feedback relay 122 operates (FIG. v1) as the master contactor 108 operates. As the safety standby signal is detected by standby circuit 138 (FIG. 2) in the received signals, standby relay 144 operates to enable an interlock relay 152 to provide a lock-in circuit for the master drive circuit 68. The master drive control group has now operated the system to the standby condition.

When the operator moves one of the transmitter control levers, such as Trolley (FIGURE 1) to either the forward or reverse positions, a signal message or word is transmitted which includes the three frame markers, a safety operate pulse during the fourth time period and a command pulse in the fifth or sixth time period (i.e., fifth if the lever was moved to F and sixth if the lever was moved to R).

As the safety operate pulse is detected by the safety operate circuit 160 (FIG. 2) a second control group identified as the control drive group are enabled to extend power to the contacts of the motor control relays TR1, TR2, etc. (FIG. 3), if a check circuit to be describedis completed to capacitor 182. Such group in- 6 cludes safety operate relay 166, command start relay 176, control drive circuit 188 and control relays 196, 204, 210, 222. v v i As a command pulse is received in a word signal, a third control group identified as the command control group are selectively enabled. This group includes the forward pulse detectors 305, 306, etc., and the command relays such as TR1-TR4, etc. In the present example, the command pulse is received in the fifth time period and the command pulse detector 305 for channel 5 operates command relay TR1 to extend 230-vo1t DC. power over contacts 246 to the motor contactor for the trolley motor at its slowest speed. Command pulses at time periods 10 or 11 will adjust the speed of the motor to different values. Command pulses at other ones of the time periods 7, 8, etc., will effect the operation of the other motors, or adjustment of the speed of the motors as indicated above.

The manner of operation of the controlcircuitry to effect such manner of operation in response to receipt of the incoming word signals is now set forth.

SPECIFIC DESCRIPTION OF CONTROL CIRCUITRY When the operator moves the on-off lever.to the ON position, signals are transmitted continuously, each of which includes the three frame markers, a standby pulse during time period 4 and sync pulses at each of the other time periods. At the receiver, the transmitted signals detected by antenna 10 are detected by receiver 12 and passed over receiver IF amplifier 16, conductor 18 and the decoder circuit 20 to the frame detector monitor 26 and repetition rate monitor 28.

The frame detector monitor circuit 26 measures the pulse widths and spacings of the frame marker A and frame marker B and checks the time elapsed between the frames. If the proper frame pulse pattern is detected ten consecutive times, frame detector monitor circiut 26 passes an enabling signal over path 30 to the monitor output 34.

The repetition rate monitor 28 checks the sync pulses which are transmitted in each time period after the frame marker (it being assumed that no command pulse has been sent), and if at least one hundred of these pulses pass the width and spacing check, a go-ahead signal is transmitted over path 32 to the monitor output circuit 34. Monitor output circuit 34 provides a monitor signal over conductor 38 to prepare a lock-in signal for the master drive circuit 68 in a manner to be described more fully hereinafter. Monitor output circuit 34 also provides an enabling signal over conductor 36 to the monitor drive circuit 40 in the first control group which operates to place the equipment in the standby condition as will now be described.

STANDBY CONDITION In the event that the equipment is properly reset, a charging circuit exists for capacitor 60 which extends from source conductor 52 (+24 volts) over contacts 124, 130, 102, 92, resistor 68, contacts 48 and capacitor 60 to the ground conductor 54, and capacitor 60 is normally charged with a positive potential. In response to the enabling signal, monitor drive circuit 40 which basically comprises a video signal rectifier provides a positive signal to the base of transistor 42 which conducts, and completes an energizing circuit for the master start relay 46, which circuit extends from source conductor 52 (+24 volts) over master start relay 46, resistor 44, and transistor 42 to ground conductor 54. A parallel circuit is simultaneously completed from conductor 52 over resistor 55, lamp 56 and transistor 42 to ground conductor 54. Lamp 56 lights to indicate the receipt of an enabling signal from the monitor output circuit 34.

Master start relay 46 operates, and at its contacts 48 interrupts the charging circuit for capacitor 60, and at its contacts 50 connects charged capacitor to the master drive circuit 68 to provide enabling potential thereto.

' lWith ,the'connection of the potential onv the charged capacitor '60 to master drive circuit 68 by the master start relay 46, maserdrive circuit 68 which basically comprises a dual drive,circuit responsive to both a DO. signal from capacitor 60 and a video Signal from monitor output circuit.34, provides a positive pulse to the base elements of ,t r ansistorsj70, 78 which turn on. Transistor 78 turns on to cor nplete an energizing circuit for driving relay 82, the circuitextending from +24 volts on conductor 52 over resistor: 84,', the winding of relay 82, transistor 78, and resistor. 80 to ground, Transistor 70 turns on simultaneousv:ly andfcompletesan energizing circuit for driving relay 74, which circuit extends from conductor 52 (+24 volts) over resistor 76,'t he winding of relay 74, transistor 70 and resistor 72 to ground conductor 54.

' Driving relays 74 and 82 operate, and driving relay 82 atits, contacts 83 completes an obvious energizing circuit for relay. 94, and driver relay 74 at its contacts 75 completes an obvious driving circuit for relay 84.

Master relays 84 and 94 each have a set of four contacts (86388, 90, 92 and '96, 98, 100, 102 respectively) the contacts of one set of four being connected in the same control circuits as the. contacts in the other set of four. Master relays 84 and 94 operate and at their corresponding contacts 86., 96 prepare a point in the 1l5-v0lt powercircuit to the crane motorcontrol relays, such/as TRl, TR2, etc. (FIG. 3); at their corresponding contacts 88, 98 complete an energizing circuit for the main motor contactor 108; at their corresponding contacts 90, 100 prepare a holding circuit for master drive circuit 68; and at their'corresponding contacts 92, 102 interrupt a further point in the charging circuit for capacitor 60.

Master contactor 108 operates over the circuit which extends from conductor 104 of the 230-volt D.C. source over contacts 88, 98, the winding of master contactor 108 to the second conductor 106 of the 230-volt D.C. source.

As the master contactor 108 operates, it is effective at its contacts 110, 112 to connect 230-volt DC. power over supply conductors 114, 116 which as will be shown provide the power to the motor contactors for the trolley, bridge. and hoist motors. Master contactor 108 at its contacts 110,. 112 also completes an energizing circuit for the master feedback relay 122, which extends from the power source conductor 104 over contacts 110, conductor 118, resistor 123, the winding of relay 122, conductor 120, and contacts 112 to the second power source conductor 106.

Master feedback relay 122 operates, and at its contacts 124, 130 interrupts a further point in a charging circuit for capacitor 60, at its contacts 126, 128 further prepares the holding circiut for master drive circuit 68.

During this period (it being recalled that at least ten successive signals including the proper frame pattern must be correctly received), the standby pulse (time period 4) is fedby' the decoder circuit over conductor 22 to the safety standby circuit 138 which checks the width and spacing measurements of three successive signals, and if the pulse pattern is correct (i.e., approximately 100 sync pulses) standby circuit 138 provides an enabling signal over conductors 140, 142 to the safety standby relay 144. Safety standby relay 144 operates, and at its contacts 146 complete an energizing circuit for the control ready lamp 186 and in parallel therewith a charging circuit for capacitor 182, the energizing circuit extending from +24 volt potential on conductor 52, over contacts 168, 146 and the series protection circuit including contacts 212, 224,242, 250, 266, 272, resistor 177, contacts 178 and capacitor 182 to ground conductor 54, and in parallel therewith over resistor 184 and lamp 186 to ground conductor 54. Capacitor 182 is charged over such path, and lamp 186 lights to indicate that the equipment has received the standby pulse.

, Safety standby relay 144 at its contacts 146 also completes an energizing circuit to the control interlock relay 152, the circuit extending from +24 volts on a 8 p a conductor 52, over contacts 168, 146, the winding of relay 152 to ground conductor 54. H I

Control interlock relay 1 52 operates and at its contacts 156' extends the AC. monitor signal from monitor output circuit 34 over conductor 38 to the masterdrive circuit 68 to provide a holding circuit for circuit 68 and thereby master drive relays 74, 82 and master relays 84, 94. More specifically, the holding circuit completed by the control interlock relay 152 extends'from the monitor output circuit 34 over conductor 38, contacts 156, conductor 157, contacts 126, 128, 100, 90 to the holding input on the master drive circuit .68. The circuit'is also extended'over resistor 93'and lamp 91 to energize the same as a further indication of the standby condition of the circuitry and the operated condition of the relays in "the first group. i i I The holding signal on the'second input circuit for master drive circuit 68 maintains transistor.70, 78 turned on, which, turn, .hold master drive ,relays74, 82 and master, relays 84, 94 energized, even though the signal provided by capacitor to the first enabling circuit for master drive circuit 68 has beenterminated (i .e., capacitor 60 has been discharged). If the,secor1 d enabling circuit to master drive circuit 68 is not completed, master relays 84, 94 obviously willnot be locked in, and as a result thereof relays 84, 94, contacts 88,98 will not maintain the master contactor 108 energized, and the command signals subsequently received 'will be ineffective.

The circuitry is now in the standby condition awaiting receipt of a command pulse in the signal messages being transmitted by the transmitter device :I'.

OPERATION RESPONSIVE TO COMMAND SIGNAL (a) Safety operate pulse As the operator moves one of the transmitter control levers from its neutral position, a safety operate pulse (time period 3) will be provided in the next signal word or message, and a standby pulse (time period 4) will be absent. The safety operate pulse operates the second control group. 1

For purposes of example, it will be assumed that the trolley is to be operated in a forward direction (channel 5) and at speed 3 (channel 11). Accordingly, the message received for such period of operation will comprise the three frame markers including frame A and frame'B markers, a command pulse in the safety operate time position (channel 3) and a command pulse in the time periods 5 and 11 respectively. Sync pulses will 'occur in the remaining time periods of the message. I

With thereceipt of such signal message by receiver 12, the decoded portions are transmitted over conductor 22,

and safety operate circuit 160 examines the width and spacing of the pulse received during time period 3. With detection of thesafety operate pulse in such period, safety operate-circuit completes an energizing circuit over conductors 162, 164 to safety operate relay 166 and in parallel therewith an operating circuit for command start relay 176. Safety standby circuit 138, failing to detect a standby signal in the fourth time period removes the energizing current to standby relay 144 which restores. Safety operate relay 166 operates, arid at its contacts 168 interrupts the control-ready contact string to the lamp 186 and capacitor 182, and "at its contacts 170 prepares a holding circuit for the control drive circuit 188 which will be completed as described in more detail hereinafter.

Command start relay 176 simultaneously operates'and at its contacts 180 connects the charged capacitor 182 to the control drive circuit 188 which basically comprises a drive circuit operative responsive to a DC. signal from capacitor 82 and a hold signal operative as shown hereinafter by a video signal from monitor circuit 34. Drive resistor 150 and 9, circuit 188 operates to provide a positive pulse to the base of transistors 194, 202-which turn on.

As transistor 194 turns on, it completes an obvious energizing circuit for control drive relay 196 which extends from +24 volt potential over conductor 52, resistor 200, the winding of driverrelay 196, and transistor 194 to ground conductor 54. As transistor 202 turns on, it completes a circuit for drive relay 204 which extends from 24 volt potential over conductor 52, resistor 208, the winding of drive relay 204, and transistor 202 to the ground conductor 54. As transistor 202 turns on, it completes a circuit for drive'relay 204 which extends from 24 volt potential over conductor 52, resistor 208, the winding of -drive.relay 204, and transistor 202 to the ground conductor 54. Drive relays 196 and 204 operate, and at their contacts 198, 206 respectively complete obvious energizing circuits for control relays 210, 222.

Control relays 210, 222 operate, and at their series connected contacts 212, 224 interrupt a further point in the energizing circuit for the capacitor 182, and at their contacts 214, 226 prepare a point in a holding circuit for control driving circuit 188 (which is completed. in a manner to be described) and at their contacts 216, 228 further extend one side of 115 volt potential on conductor 53 to one side of the motor control relays TRl-TR4, BR1BR4, HRl-HR4 and AU1-AU2 (FIGURE 3).

Control relay 210 at contacts 218 further extends the 230 volt potential circuit on conductor 116 to thecontrol contacts-on the bridge control relays BR1BR4, at its contacts 220 further extends the 230 volt supply circuit on conductor 116 to the contacts (such as 246, 254, 258, 262) on control relays TR1-TR4 for the trolley motor contactors. Control relay 222 at its contacts 230 similarly extends 230 volt power to the control contacts on control relays HRl-HR4 for the hoist motor contactor.

(b) Command pulse It will be recalled that the incoming signal included a safety operate pulse in time slot 3 and a command pulse at the time slot 5 and at the time slot 11 of the message for the purpose of energizing the third control group in the energization of the trolley forward relay TRl and the trolley speed three relay TR4.

With the detection of the command pulse in the fifth time slot, channel detector equipment 305, which basically comprises a pulse amplifier and relay, completes an energizing circuit to-trolley forward relay TRl, and as the command pulse occurs in time slot 11, the channel detection equipment 311 completes an energizing circuit to speed control relay TR4 which selects speed position 3 for the trolley motor. It will be apparent that the command pulse in slot 6 occurred approximately 4 /2 milliseconds after the safety operate pulse, and the commandpulse in time slot 11 occurred approximately /2 microseconds after the safety operate pulse. Accordingly, the trolley forward relay TRl and trolley speed 3 relay TR4 will operate substantially concurrently with safety operate relay 166, and standby relay 144 will restore at approximately the same time.

As standby relay 144 restores, it is effective at contacts 146 to interrupt the energizing circuit for interlock relay 152, which restores to interrupt one holding circuit to master drive circuit 68. However, since safety operate relay 166 has now operated, contacts 170 are closed to hold master drive circuit 68' over the circuit which extends from monitor output circuit 34 over conductor 38, contacts 170, conductor 157, contacts 126, 128, 100, 90 to the master drive circuit 68.

Further, standby relay 144 and interlock relay152 restored and with relay TRl, 166, 210, 222 in the energized condition, a holding circuit is completed for the control drive circuit 188 which extends from monitor output circuit 34 over conductor- 38, contacts 170,148, 214, 226, 244, 154 to the second input circuit for control drive circuit 188, Thus, the master drive circuit 68 and the control drive circuit 188 are held operatedfor the ensuing period in which the incoming signals enable monitor output circuit 34 to provide a monitor signal over conductor 38.

The trolley motor control relay TRl in operating is further effective at its contacts 246 to extend the .230 volt source potential from conductor 104 (FIGURE 2) over contacts 110, conductor 116, resistor 221, contacts 220 and 246 to conductor 247 which is connected to the trolley motor contactor (not shown) which effects operation of the trolley motor in the forward direction. Trolley speed 3 relay TR4 is operative at its contacts 262 to extend the same potential over conductor 261 to the speed control circuitry which adjusts the speed of the trolley to speed 3.

The manner in which different command pulses can be provided in the signals to effect control of the different crane motor control relays TR1-TR4, 'BR1BR4, HR1 HR4, AUXl-AUXZ in the operation of the crane in any desired manner will be apparent from the foregoing description. I

In one embodiment five different crane motors each with five speeds in forward and reverse were controlled with equipment connected in the manner desired. Such unit requires approximately 10,000 unique pulse combinations or codes which are readily provided by the control equipment set forth hereinabove. Variations of such control circuitry will be apparent. Y

CONTROL CIRCUIT RESTORATION RESPONSIVE TO TERMINATION OF SIGNAL WORDS WITH COMMAND RULES At such time as the transmitter levers are returned to normal, the command pulses in channel 5 and channel 11 will be terminated, the safety operate pulse will no longer be transmitted in the third time slot, and the safety standby pulse will be transmitted in the fourth time slot condition. The equipment will responsively restore to the standby condition.

More specifically, as the command pulses are no longer detected in channels 6 and 11 by channel detector 305, 311, trolley forward relay TRl (240) and trolley speed 3 relay TR4 will restore to interrupt the 230 volt A. C, power which was extended over contact conductors 246, 262 to the trolley motor contactors and the speed control circuitry for the trolley motor. Further, with termination of the safety openate pulse in channel3, safety operate circuit interrupts the energizing circuit for safety operate relay 166 which restores with command start relay 176.

The safety standby circuit 138 detects the occurrence of a standby pulse in channel 4 and completes an energizing circuit for standbyrelay 144, which in turn reestablishes the energizing circuit to interlock relay 152. As relay 152 operates, it is effective at is contacts 156 to reestablish the second holding circuit for the master drive circuit 68 which has been interrupted at contacts by the restoration of the safety operate relay 166. Relay 152 at its contacts 154 interrupts the holding circuit for control drive circuit 188.

Command start relay 176 restores with the safety operate relay 166 and reestablishes the charging circuit for capacitor 182. The first input circuit for control drive circuit 188 is interrupted at contacts 180, and as noted above the second input circuit for control drive circuit 188 was interrupted with operation of interlock relay 152. As a result thereof, transistors 194, 202 are switched off, control relays 196, 204 are restored, and control relays 210, 222 are restored. The equipment is now in the standby condition awaiting the receipt of further signal words with command pulses.

In the event that the attendant now turns the transmitter on-off lever to the off position, the video on output circuits 36 and 38 will be terminated, and master drive circuitry 68 will be restored to return the receiver to the off condition. That is, the loss of a video signal on conductor 36 will result in monitor drive circuit 40 controlling transistor 42 to switch off and restore relay 46, which at its contacts 50 interrupts the first energizing circuit for master drive circuit 68. The loss of the monitor signal on conductor 38 terminates the holding signal on the second input circuit to master drive circuit 68. p

' The master drive circuit 68 responsively controls transistor 70, 70A to twitch off, and thereby effect the release of master'drive relay 74, 82 and master relays 84, 94 to further interrupt the energizing circuit for the second input circuit to master drive circuit 68.

With the absence of the standby pulse, the safety standby relay 144 is restored, and at its contacts 156 further interrupts the energizing circuit for the secondinput circuit to master drive circuit 68. Standby relay 144 at its contacts 146 also interrupts "the energizing circuit for capacitor 182. The equlpment is now restored to its normal off condition.

CONTROL CIRCUIT PROTECTIVE ARRANGEMENTS Over-travel cranes are used to carry loads of many different types, many of which are of excessive weight, heat or size. As a result, it is extremely important that the control circuitry operate instantaneously and with maximum reliability. Novel safety circuits included in the control circuitry set forth hereinabove are fundamental to the provision of circuitry which operates in such manner.

Initially, it will be apparent that the basic circuit sequence inherently incorporates a high order ofsa-fety. That is, in the provision of a frame detector which requires that four different pulse widths and spacings preface each word signal, ten consecutive times, and further that one hundred sync pulses be correctly received before the receiving equipment will respond, is in itself a substantial degree of protection against malfunction. In addition, moreover, the receiver control circuitry relay includes a number of safeguards. Thus, if a command relay, such as trolley reverse relay 248 should fail, or if its contacts 254 should remain closed after the incoming signal requesting such command has terminated, the command enabling relay 210 in restoring after the command pulses are no longer received, will be efi'ective at its contacts 220 to break the energizing circuit which extends over contacts 254 to the trolley reverse contactors when the transmitter trolley control lever is returned to the neutral position (i.e., the video enabling output signal monitor output circuit 34 will be interrupted, and the control drive circuit 188 will effect the restoration of driver relays 196, 204 and control relays 210, 222). The energizing circuit "for each of the other motor contactors is protected in a similar manner.

Even further, if the contacts 254 on a command relay, such as 248, and the enabling contacts, such as 220 on enablingrelay 210 should both remain in the closed position after the received command is terminated (an extremely unlikely and remote possibility), with the movement of the transmitter on-o switch to the off position, the master contactor 108 will be restored to interrupt the power to each of the motor contactors.

Two additional safety provisions of significance are further included in the circuit arrangement which comprise (a) special redundant circuits, and (b) an automatic relay checking system.

Redundant sequence was incorporated by using two relays instead of one in critical contact circuits, each of which has a separate drive system. As a result, if one of the relays should operate incorrectly, the crane will not operate. Alternatively if either one of the relays is momentarily deenergized, the checking circuit detects the malfunctioning to interrupt the relay power and thereby prevent operation of the crane. If the malfunction continues, the circuit will be interrupted and it will be impossible to restore the system. Automatic relay checking is achieved in several manners. Initially one safeguard is provided by dividing the relays into three groups identified hereinbefore and connecting the circuits so that the three groups must operate in tandem before acrane motor can be energized. Thus to energize the trolley forward contactors, the group of relays controlled by master drive circuit 40 must operate, the group of relays controlled by control drive circuit 188 must operate correctly, and the group of function relays controlled by the channel detectors, such as 305, must be operated correctly. If any relay in any group fails, the circuit will not be completed to the desired motor contactor.

Since the master drive group 40 requires the correct receipt of the basic on signal and the standby signal, the control drive group requires the correct receipt of the safety operate signal, and the functional relay group requires the receipt of a specific command, it is apparent that the possibility of malfunction inherently is greatly reduced.

As a second safeguard the circuit further requires that the relays in each group are in the normal off conditioni.e., that none of the relays (or contacts on the relays) are jammed or stuck in the wrong condition.

In the first or master drive group, the master relays 84, 94 and master feedback relay 122 must be in the deenergized condition preliminary to completion of a circuit to the master drive circuit 68. If any one of the relays 84, 94 or 122 is not in its deenergized condition (or one of the contacts 124, 130, 102, 92 is stuck open) capacitor 60 will not be charged, the master checking circuit will not operate, and no control can be accomplished.

An identical checking operation is performed .by the control relays 210, 220 and the function relays TR1, TR2, BRl, BR2, I-IRl, HR2, etc., in the control drive group. That is, once the standby circuit 138 operates the standby relay 144 to close its contacts 146, the charging capacitor 182 will be charged only if the motor control relays 210, 220 are deenergized, and each of the motor control relays TR1, TR2, for the trolley motor control relays BRl, BR2 for the bridge 264, 270 and motor control relays HRl, HR2 for the hoist 276, 278 are in the restored condition so that contacts 212, 224, 242, 250, 266, 272 are closed to complete a charging circuit for capacitor 182. If any relay is held energized (or any one of the contacts is stuck open) control drive circuit 188 will not be energized and the system will not operate.

The relay circuits are thus inherently connected to provide fail-safe operation even if the contacts of a relay should stick or jam in the closed position. Summarily, safety techniques areaccomplished as follows:

(a) The relays are divided roughly into three groups which operate in tandem and the appropriate relays in all three groups must be energized before a crane motor can be operated.

(b) The relays within each group are first checked in the off condition to be sure that none are jammed or stuck in the energized position and only if this check is complete can the relays be subsequently energized.

(c) Redundant relays are used to provide normal tumofi in the event of a relay malfunction. However, the system cannot be restored until the malfunction has been cleared. In such manner maximum safety of operation is achieved.

While only certain particular embodiments of the invention have been shown and described, it is apparent that modifications and alterations may be made therein, and it is intended in the appended claims to cover all such modifications and alterations as may fall within the true spirit and scope of the invention.

What is claimed is:

1. In a remote control system for controlling the extension of power from a source to the trolley, bridge, and hoist motors of an overhead crane including transmitter means for transmitting signal words, each of which words has a frame marker and certain of which have command signals, receiver means a master drive circuit means connected to said receiver means operative only responsive to receipt of a signal word, control drive circuit means connected to said receiver means operative only responsive to receipt of a signal word including a command, a function selection means for each of said motors connected to said receiver means, each of 'w'hi ch is operative responsive to a different one of said command signals, and a series circuit for extending power from said source to one ofsaid motors only with simultaneous closing of three contact sets including a'firstcontact set controlled toclose only responsive to operation of'said master drive circuit means, a second contact set controlled'to close only responsive to operation of said control ,drive circuit means, and a third contact set controlled to closeonly responsive, to operation of the function selection means for said one motor, and disabling means controlled bysaid function selection means to prevent reoperation of said control drive circuit means responsive to one of said function selection means remaining in the enabling condition for its motor subsequent to termination of the commandsignal therefor.

2. A system as set forth in claim 1 in which said disabling means includes a check circuit for said control drive circuit means, and a plurality of contacts connected in series in said check circuit controlled by each of said function selection means to complete said check circuit only when all of the function selection means are properly restored.

3. In a remote control system for controlling the extension of power from a source to the trolley, bridge, and hoist motors of an overhead crane including transmitter means for transmitting signal words, each of which signal words has a frame marker and certain of which have command signals, receiver means, a master drive circuit means connected to said receiver means operative only responsive to receipt of a signal word including a command signal, control drive circuit means connected to said receiver means operative only responsive to receipt of a signal word including a command signal, a function selection means for each of said motors connected to said receiver means, each of which includes switch means controlled to connect power to its associated motor responsive to detection of a different one of said command signals, means for extending power to a motor only responsive to operation of said master drive circuit means, said control drive circuit means and the switch means in the function selection means for said motor, and means for preventing operation of said control drive circuit means responsive to receipt of the assigned command signal subsequent to a failure of a switch means in one of said function selection means to reset.

4. In a remote control system for controlling the extension of power from a source to the trolley, bridge, and hoist motors of an overhead crane including transmitter means for transmitting signal words, certain of which signal words has a frame marker and a stand-by signal and others of which have a frame marker, an operate signal, and a command signal, receiver means, a master drive circuit means connected to said receiver means operative only responsive to receipt of a signal word, control drive circuit means connected to said receiver means operative only responsive to receipt of a signal word including a command signal, a function selection means for each of said motors connected to said receiver means, each of which selection means is responsive to a different one of said command signals and each of which includes a relay, power supply means for extending power to a motor only responsive to operation of said master drive circuit means, and the relay in the function selection means for said motor, a series energizing circuit for said control drive circuit means comprised of at least one contact on each of said relays in said function selection means, and means for completing said series circuit only responsive to reset of each of said relays in said function selection means and receipt of a signal word which includes an operate signal and the absence of a standby signal.

5. A system as set forth in claim 4 in which said control drive circuit means includes relay means having a first set of contacts in said power supply means which are closed only when said relay means are operated, and a second set of contacts in said series energizing circuit which are closed only when said relay means are restored.

6. A System asset forth in claim 4 in which said master drive circuit means include means for energizing a master contactor to couple power to said power supply means, and interlock means operative responsive to receipt of. said signal word to complete-a holding circuit to said master drive circuit means during the period a signal word is received and said, master contactor is operated.

7.' In a remote control system for controlling the extension of power from a source to the trolley, bridge and hoist motors of an overhead crane including transmitter means for transmitting signal words, control means including a master contactor for'providing A.C. power from a source to said motors, and at least one relay operable from afirst position to a second position to operate said master contactor, drive circuit means for controlling operation of said one relay, a check circuit for use in controlling energization of said drive circuit means in response to receipt of a signal from said transmitter means including means for determining said one relay as being in said first position prior to enablement of said drive circuit means and for preventing enablement of said one relay by said drive circuit means whenever said one relay is not in said first position.

8. An arrangement as set forth in claim 7 in which said check means includes a capacitor, and contacts on said one relay for completing a charging circuit to said capacitor with said one relay in said first position, and means for connecting said charged capacitor to said control means only responsive to receipt of a signal from said transmitter means.

9. An arrangement as set forth in claim 7 which includes a holding circuit for said drive circuit means, and contact means on said one relay for completing said holding circuit with operation of said relay to said second position.

10. In a remote control system for controlling the extension of power from a source to the trolley, bridge and hoist motors of an overhead crane including transmitter means for transmitting signal words, control means including a master contactor for providing A.C. power from a source to said motors, a first and a second control relay for controlling operation of said master contactor means, circuit means for simultaneously operating said first and second relay from a first position to a second position only in response to receipt of a signal from said transmitter means, and check means for checking said first and second relays in said first position prior to enablement of said circuit means and for preventing energization of said first and second relays whenever said first or second relay is not in said first position.

11. An arrangement as set forth in claim 10 in which said check means includes an energizing circuit for said circuit means, and contacts on said first and second relays connected in series to complete said energizing circuit to said circuit means only with said first and second relays in said first position.

12. In a remote control system for controlling the extension of power from an alternating current power source to the trolley, bridge and hoist motors of an overhead crane, a selection relay for each of said crane motors having a first and a second position, contact means on each selection relay for extending power to its associated motor with operation of its relay to its second position and for interrupting said extension of power to said motor with said relay in said first position, at least one control 15 relay for providing AC. power to said contact means, drive circuit means for operating said control relay, and a check circuit comprising means connecting a contact on each of a plurality of said selection relays to enable said drive circuit means only with each of said selection relays in said first position. I

13. An arrangement as set forth in claim 12 which'includes a holding circuit for said drive circuit means, and contacts on each selection relay for completing said holding circuit responsive to operation of the selection relay to its second position.

14. An arrangement as set forth in claim 12 which includes a second control relay connected to operate simultaneously with said first relay from a first to a second position, and said check circuit includes contacts on said first and second control relays connected in series to close said check circuit only with said control relays in said first position. 15. An arrangement as set forth in claim 12 which includes input means over which standby and operate signals are received and in which said check circuit includes a capacitor, and means for completing a charging circuit to said capacitor responsive to receipt of a standby signal over said input means, and means for connecting said charged capacitor to said drive circuit means responsive to receipt of an operate signal over said input means.

' 16. In a remote control system for controlling the extension of power from an alternating current power source to the trolley, bridge and hoist motors of an overhead crane, transmitter means for transmitting signal words, a selection relay for each of said crane motors, means for operating each of said relays from a first position to a second position responsive to receipt of a preassigned signal word, contact means on each selection relay for extending power to its associated motor with operation of its relay to its second position, at least one. control relay for providing-A.C. power .to said contact means, drive circuit means for operating said control relay, and a check circuit comprising means connecting a contact on each of said selection relays to enable said drive circuit means only with each of said selection relays in said first position.

References Cited UNITED STATES PATENTS ORIS L. RADER, Primary Examiner.

B. A. COOPER, Assistant Examiner. 

